(1) Field of the Invention
The present invention relates generally to spectacles and in particular to spectacles with double polaroid lenses of which one having multiple non-polarized aperture-like areas thereon by perforating or de-polarizing of portions of the lens.
(2) Description of the Prior Art
Eyeglasses with polarized elements are well known in the art. The concept of providing variable light transmission characteristics to an ophthalmic device by employing light polarizing elements which may be rotated with respect to each other is not new. For background information on systems of this type reference should be made to U.S. Pat. No. 2,005,246 issued to Edwin H. Land on Jun. 18, 1935, U.S. Pat. No. 2,251,330 issued to Murray N. Fairbank on Aug. 5, 1941, U.S. Pat. No. 2,565,362 issued to V. K. Eloranta on Aug. 21, 1951, U.S. Pat. No. 3,944,346 issued to A. Shindler on Mar. 16, 1976, U.S. Pat. No. 4,119,369 issued to V. K. Eloranta on Oct. 10, 1978, U.S. Pat. No. 4,113,364 issued to M. V. Dussich on Sep. 12, 1978, U.S. Pat. No. 4,386,832 issued to G. Nannini on Jun. 7, 1983. Each of the forgoing generally related to devices for providing variable light transmission by employing light polarizers. In those patents the light transmission will be cut down almost completely if the direction of the polarizers are held perpendicular to each other. This will be dangerous when the application is used as a sunglass of an automobile driver. Referring to U.S. Pat. No. 3,867,020 issued to H. N. Braunhut on Feb. 18, 1975 which teaches a polarizer set with exactly centrally located aperture and concentrically arranged opaque elements, which prevent light transmission having an angle of incidence greater than a predominant angle of acceptance. It is particularly used to control viewing angle. While fishing, it can eliminate the glare of water surface. But the light transmission is not homogeneously through the lens set, and because the aperture is single and exactly centrally located, the offset of visual axis due to pupil distance variation will significantly influence the actual application.
The present invention possesses many advantages over above mentioned designs in that it provides uniformly distributed multiple light transmission apertures and is relatively easily approached by visual axis. Centering of the application to visual axis is not so necessary. It eliminates the risk of totally shut down the light by providing residual light transmission through the multiple apertures.
In the art of photography, picture will be clearer when it is taken by a small aperture than a larger aperture. This is because the smaller aperture will increase the depth of focus. This is also true in our invention, by properly selected aperture size. When the light transmission is cut down maximally, the light transmission is only through the apertures, and it acts like reduced camera aperture to provide an increased depth of focus to the retinal image of the viewer. Hence it will increase the visual acuity of the viewer.